Treatment of non-woven cellulosic fabrics with weak acid aminotriazine resin colloids



United States Patent 0 TREATMENT OF NON-WOVEN CELLULOSIC FAB- RICS WITH WEAK ACID AMINOTRIAZINE RESIN COLLOIDS James K. Dixon, Riverside, Conn., assignor to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Application April 10, 1952, Serial No. 281,675

11 Claims. (Cl. 117-145) This invention relates to the treatment of non-woven cellulosic fabrics. More particularly, it relates to a method for increasing the tensile strength of non-woven cellulosic fabrics wherein substantially all the fibers are oriented in one direction.

In the past, Woven fabrics including cotton have been treated with solutions of condensation products of aldehydes and aminotriazines containing acids as curing agents.

It has also been proposed to treat non-woven, nonoriented cotton fibers with a solution containing melamine, formaldehyde, hydrochloric acid, and a softening agent in order to improve the properties of the cotton fibers for use in the manufacture of felt fabrics or hat bodies.

I have recently discovered that the application of weak acid cationic aminotriazine-aldehyde resin colloids such as, for example, an acetic acid colloid of methylatedtrimcthylol melamine, to woven cotton fabrics provides good shrinkage control with no loss in the tensile strength of the cotton. Processes for so treating woven cotton fabrics are described and claimed in my copending application, Serial No. 123,791, filed October 26, 1949, entitled Treatment of Woven Cotton with Weak Acid Aminotriazine Resin Colloids.

It is an object of the present invention to provide a process for treating non-woven cellulosic fabrics wherein the fibers are substantially all oriented in one direction.

It is another object of the present invention to provide a process for treating non-woven cotton fabrics in which substantially all-of the cotton fibers are oriented in one direction.

"Another object of the present invention is to provide a process-for treating non-woven viscose fabric in which substantially all of the viscose fibers are oriented in on direction.

Still another object of the present invention is to provide a process for thetreatment .of'non-Woven fabrics containing a mixture of cotton and viscose fibers substantially all of which are oriented in a single direction.

A further object of the present invention is the production of a non-woven cellulosic fabric of increased tensile strength.

It is a further object of the present invention to in crease the tensile strength of non-woven cellulosic fabrics in which substantially all of the fibers are oriented in one direction, the increase occurring both in the direction of the fibers and in the direction perpendicular to that of the fibers.

The above and other objects are attained by treating a fabric composed of substantially unidirectionally oriented, non-woven cellulosic fibers with a colloidal aqueous solution of a polymerized aldehyde condensation product of an aminotriazine which contains a watersoluble, saturated aliphatic hydrocarbon or hydroxyhydrocarbon monocarboxylic acid.

The invention will be described in greater detail in conjunction with the following specific examples in which 'ice proportions are given in parts by weight unless otherwise noted. The examples are merely illustrative and it is not intended that the scope of the invention be limited by the details therein set forth.

Example 1 A non-woven fabric known as cotton Masslinn is used in this and certain of the following examples. The cotton fibers in Masslinn are substantially all oriented in one direction, and the parallelized fibers are bonded together at intervals in a. direction perpendicular to the direction of the fibers with a thermoplastic resin of the polyvinyl acetate type, the resin constituting generally from about 6%-l0% of the weight of the fabric. Although the tensile strength of Masslinn will depend to a degree upon the Way in which it is mechanically processed or treated, it will be apparent that the tensile strength perpendicular to the direction of the fibers is very low and several fold less than the tensile strength in the direction of the fibers.

Suitable samples of the Masslinn are placed in shallow vessels and covered with various resin colloid solutions. The wetted out samples are fed through squeeze rolls to remove excess resin solution and then dried at about 140 C. for 6l0 minutes.

The tensile strength of each of the resin-treated samples is then measured on a Suter tensile tester by the grab method using 3 inch length.

The resins used for treating the Masslinn are as follows:

lowing table:

Tensile Strength Percent 111 Resin Add-on Fill It is interestiiig to note that in the' ca'se of resin A there is a marked decrease in the tensile strength at the higher resin concentrations.

- colloid solution extracting and/or redistributing the polyvinyl acetate resin binder present in Masslinn. This theory seems to be borne out by the fact, as will-be demonstrated in later examples, that when non-woven fabric containing no resin binder is similarly treated with the resin colloid solutions there appears to be a linear relationship between resin pick-up and tensile strength. Furthermore, it is believed to explain the slight apparent decrease in warp tensile strength at 10% Resin B pick-up. In this instance it should be noted that there is an over-all increase in tensile strength since that in the fill direction increases proportionately far more thanthat of the Warp decreases.

Similar treatment of Masslinn with non-colloidal methylated trirnethylol melamine and an acid-liberating catalyst produces no change in the tensile strength of the fabric.

Eatented May 17, 1955 This is probably due'to' the'resin Example 2 Samples of all rayon Masslinn are impregnated with Resin A as described in Example 1, and the tensile strength of the treated samples is observed. Results are as follows:

sliensilti1 Percent rcugt Resin Adcbon in lbs,

'Fill sarily any predictable relationship between the changes in tensile strength observed in woven and in non-woven goods.

Example 3 Example 1 is repeated with Masslinn containing both cotton and rayon fibers in a 50:50 proportion with the following results:

- Percent trengt R951 Add-0n in lbs,

Fill

Example 4 In this example a non-woven cotton material composed of substantially unidirectionally oriented fibers with no resin binder is used instead of Masslinn. Since the material has very little tensile strength in the dry state and even less when wet, it may be desirable to support it during the application of resin thereto.

Samples of the non-woven material are supported on sheets of tin plated soft steel 0.012 thick having a smooth surface and resin colloid solutions are carefully poured thereover. The tin sheets with the so-wetted out samples are then passed through squeeze rolls as in Example 1. The material is stripped from the sheets and cured by heating for about 610 minutes at about 140 C.

The result of tensile strength measurements on the samples of treated material are set forth in the following table:

Tensile Percent Strength Add-on inlbs,

Fill

It will be noted that at low concentrations of Resin A there is considerable increase in the tensile strength which reaches a maximum at between about and 10% pick-up.

Example 5 with glacial acetic acid, the material is washed with distilled water until the wash water is free of any turbidity produced by the polyvinyl acetate or like binder present in the Masslinn. The water is then replaced by acetone and the covering glass cloth is removed while the material is still wet out with acetone. Under these conditions it is possible to strip the fabric off the glass cloth supporting it. It is then air dried.

Samples of non-woven material obtained as described above are treated with an acetic acid colloid of methylated trimethylol melamine and the tensile strength measurements are summarized in the following table:

ercunt treugth lesm Add-on lnlb.

Fill

Example 6 The procedure of Example 5 is following starting with all cotton Masslinn instead of all rayon Masslinn and removing the resin binder therefrom. Tensile strength results are as follows:

Upon examination and comparison of the tensile strength results for Masslinn samples (Examples 1 and 2) and Masslinn samples with the polyvinyl acetate binder removed (Examples 5 and 6) treated with resin A, there is indication of an increasing difference between the tensile strengths as the concentration of resin is increased. This is most pronounced on the all cotton type fabrics. Assuming that on the Masslinn the polyvinyl acetate or like resin binder exists as an inert material one would expect that the difference in tensile strengths between the two fabrics would be constant. Since the difference is a variable, it appears that the acid colloid may extract or redistribute the resin binder.

PREPARATION OF RESIN A 125 parts of aqueous methylated trimethylol melamine prepared according to Example 2 of British Patent No. 566,347 (0.4 mol) 806 parts water 72.4 parts glacial acetic acid (1.2 mols) The methylated trimethylol melamine is dissolved in the water and the acetic acid is added to the solution with rapid stirring. A 10% resin solids colloid solution is obtained after 24 hours ageing at 60-70 F.

PREPARATION OF RESIN B 99.4 parts of trirnethylol melamine (0.46 mol) 795 parts water parts lactic acid (1.16 mols) The water and acid are mixed together at 6070 F., the resin is added, and the resulting combination is shaken until substantial solution takes place. The resin is then filtered to remove any traces of undissolved resin and the solution is permitted to age at 60-70 F. until a blue haze characteristic of colloid formation appears.

PREPARATlON GF RESIN C 216 parts of trimethylol melamine (1 mol) 1764 parts of water parts of glacial acetic acid (3 mols) The same procedure as for the is followed.

Aminotriazines containing two or three reactive amino groups, i. e., containing hydrogen atoms attached thereto, such as melamine, N-guanylmelamine, ammeline, the guanamines including formoguanamine, acetoguanamine, propioguanamine, phenyl guanamine, etc., and N-alkyl-, N-aryl an d N-aralkyl-substituted derivatives thereof such as N-methylmelamine, N-phenylmelamine, N-benzylmelamine, etc., which contain a hydrogen atom attached to each nitrogen atom as disclosed in U. S. Patent No. 2,197,357 may be reacted with aldehydes to form the condensation products used for preparing cationic colloidal resin solutions which may be used in the present process. Methylol melamines obtained by condensing melamine with varying amounts of formaldehyde, i. e., in molar ratios of about 1:1 to 1:20 but preferably and generally of about 1:2 to 1:6, such as trimethylol melamine, hexamethylol melamine, etc., and their water-dispersible alkylated derivatives obtained by reacting the methylol melamines with lower aliphatic alcohols such as methanol and ethanol, are preferred.

Aldehydes other than the formaldehyde of the examples, such as formaldehyde-yielding materials including paraformaldehyde and hexamethylenetetramine, benzaldehyde, furfural, acetaldehyde, paraldehyde, etc., may be used.

In general the polymerized aminotriazine resin colloid solutions are prepared in accordance with the teachings of the Wohnsiedler et al. U. S. Patent No. 2,345,543 using saturated aliphatic monocarboxylic acids having dissociation constants between about l.4 land 2.5 X- and water solubilities of at least about 10%. Acids included within this category are hydrocarbon and hydroxyhydrocarbon acids as follows:

Just as set forth in the Wohnsiedler patent referred to above, the exact amount of acid desirable or necessary for producing the various cationic resin colloids is variable. In general I prepare the colloidal polymerized resin solutions using from 0.5-7 mols of acid per mol of substantially monomeric aldehyde condensation product.

More specifically, in the preparation of colloidal solutions of polymerized methylated trimethylol melamine resin, I have found it advisable to use about 3 mols of acetic acid or about 1.5 mols of formic acid or from about 22.5 mols of glycolic acid for each mol of substantially monomeric methylated trimethylol melamine although satisfactory colloids can be prepared with greater or lesser amounts.

All of the resins which are useful in the process of the present invention are cationic and they impart an appreciable improvement in the tensile strength of the nonwoven fabrics, both in the direction of the fiber and in the direction perpendicular to that of the fiber.

Resin colloids made with hydrochloric or other strong acid as described in the above-referred to Wohnsiedler et al. patent may not be used in the process of the present invention since they do not improve the tensile strength of the non-woven cellulosic fabrics. It is possible to use hydrochloric acid and other relatively strong acid resin colloids if the continuous phase of the colloid is not water alone but rather a mixture of water and water-soluble polyhydric alcohol. As a matter of fact, resin colloids can preparation of resin B be prepared with reduced quantities of the weak organic acids if polyhydric alcohol is present. Such colloids are described and claimed in the Pollard U. S. Patent No. 2,417,014, and their use to increase the tensile strength of non-woven, cellulosic fabrics wherein the fibers are substantially all oriented in one direction is described and claimed in my copending application Serial No. 123,794, filed October 26, 1949, entitled Treatment of Non- Woven Cellulosic Fabrics With Modified Acid Resin Colloids.

in order to obtain the optimum effect of the present invention, the non-woven cellulosic fabric is so treated with the acid resin colloids that from about 0.5% to by weight of resin solids, based on the dry weight of the fabric, will be deposited therein. Actually there is no real lower limit since incorporation of any small amount of the resin will increase the tensile strength to some degree but for practical purposes a lower pick-up than 0.5% will not increase the tensile strength appreciably. Higher pick-ups than 25%, however, produce undesirable properties such as excessive stiffness and harsh feel, and accordingly the upper limit is a real and practical one.

The invention is not limited to any particular method of impregnation of the non-woven fabric which may be immersed in a resin solution and the excess resin removed or which may be sprayed with a resin solution if necessary or if desired. In any event special care in handling must be taken in view of the extremely low tensile strength of the untreated non-woven fabrics, particularly when they are wet.

In the examples the resin-impregnated fabrics are dried and cured at about 140 C. for from 6l0 minutes. This is merely a matter of convenience since the acid colloid produces the same tensile strength increase at much lower curing temperatures. Even air drying is sufficient, and therefore little or no heat curing is really necessary in order to obtain in the fabric a resin polymer with desirable binding properties. Generally speaking, however,

the impregnated fabric will be allowed to dry at temperatures ranging from about 400 F.

Non-woven fabrics composed of substantially unidirectionally oriented cellulosic fibers, when treated according to the process of the present invention, are likely to possess a harsh and somewhat stiif hand, this effect being dependent upon the resin concentration and increasing with increased add-on or dry pick-up of the resin. There are several Ways of improving the appearance and hand of the fabric.

In the first place, the acid colloid resins may be printed,

onto non-woven fabrics in much the same manner as the manufacturers of Masslinn apply the resin binder.

Another method involves lap calendering of dried non woven fabrics treated with the acid resin colloidsQ Samples of Masslin and non-woven fabrics containing no' .resin binder, when treated to a 4% resin add-on with acetic colloid of methylated trimethylol melamine" and run through a lap calender four times, possess an appreciably softened hand.

Moreover, the resin colloid-treated, non-woven fabrics may be hot calendered. Fabrics heated with melamine resin and then so calendered acquire a chintz-like quality. A fourth remedy involves addition to the resin acid colloid of a textile softener such as, for example, the reaction product of from 5.5-6.5 mols of ethylene oxide with one mol of a mixture of the octadecylamine salt of N-octadecyl carbamic acid and the octadecyl guanidine salt of N-octadecyl carbamic acid as described in U. S. Patent No. 2,427,242. The softening agent appears to make the surface feel less harsh.

It is an advantage of the present invention that nonwoven fabric which has been treated with a resin colloid may be dyed or pigment printed. Moreover, the treatment of the present process animalizes the fabric so that it may be dyed with acid dyestuffs. I

The treated fabrics of the present invention may be coated to obtain interesting and useful articles. For example, Masslinn treated with resin A and then coated with, for example, nitrocellulose resembles oil cloth in appearance.

Some uses for my resin-treated, non-woven fabrics are as follows: towels, napkins, doilies, dish cloths, table cloths, drapery materials, wall covering, pipe covering, milk filters, cheese press cloths, ribbon, chemical filters, etc. If they are heat pressed to a stiffness, the fabrics are useful in the manufacture of lampshades, lintless wiping cloths, etc.

Use of my resin colloid-treated, non-woven fabrics as the plies of a laminate results in the production of a laminated product of improved flexural strength, flexural modulus, hardness and tensile strength and decreased water absorbency when compared w. it one made up of plies of untreated non-woven fabric.

This application is a continuation of my application Serial No. 123,792, filed October 26, 1949 and now abandoned.

l claim:

1. A process of increasing the tensile strength of a fabric composed of substantially untwisted, unidirectionally oriented, non-woven, cellulosic fibers of the group consisting of cotton and rayon fibers which comprises treating said fabric with a colloidal aqueous solution of a cationic polymerized aldehyde condensation product of an aminotriazine having at least two amino groups and a hydrogen atom attached to each amino nitrogen atom, said colloidal aqueous solution containing from 0.5 to 7 mols of a water-soluble monocarboxylic acid selected from the group consisting of saturated aliphatic hydrocarbon and hydroxy hydrocarbon acids having dissociation constants between about 1.4 1O and x10 for each mol of substantially monomeric aldehyde condensation product, the take-up of the colloidal solution by the fabric being such as to deposit from about 0.5 to 25% by weight, based on the dry weight of the fabric, of the polymerized aldehyde condensation product in the fabric, and thereafter curing the rested fabric whereby the deposited aldehyde condensation product is in a substantially Water-insoluble condition.

2. A process of increasing the tensile strength of a fabric composed of substantially untwisted, unidirectionally oriented, non-woven, cellulosic fibers of the group consisting of cotton and rayon fibers which comprises treating said fibers with a colloidal aqueous solution of a cationic polymerized melamine-formaldehyde condcnsation product, said colloidal aqueous solution containing from 0.5-7 mols of a water-soluble monocarboxylic acid a selected from the group consisting of saturated aliphatic hydrocarbon and hydroxy-hydrocarbon acids having dis sociation constants between about 14x10 and 2.5 l0* for each mol of substantially monomeric melarninc-formaldehyde condensation product, the takenp of the colloidal solution by the fabric being such as to deposit from about 0.5% to 25% by weight, based on the dry weight of the fabric. of the polymerized melamine-formaldehyde condensation product in the fabric, and thereafter curing the treated fabric whereby the deposited melamine-formaldehyde condensation product is in a substantially water-insoluble condition.

3. A process as in claim 2 wherein the melamine-formaldehyde coudensation product is methylated trimethylol melamine.

4. A process in accordance with claim 2 wherein the melarninc-formaldehyde condensation product is trimethylol melamine.

5. A process of increasing the tensile strength of a fabric composed of substantially untwisted, unidirectionally oriented, non-woven, cellulosic fibers of the group consisting of cotton and rayon fibers which comprises treating said fibers with a colloidal aqueous solution of a cationic polymerized melamine-formaldehyde condensation product, said colloidal aqueous solution containing about 3 mols of acetic acid for each mol of substantially monomeric melamine-formaldehyde condensation product, the take-up of the colloidal solution by the fabric being such as to deposit from about 0.5% to 25% by weight, based on the dry weight of the fabric, of the polymerized melamine-formaldehyde condensation product in the fabric, and thereafter curing the treated fabric whereby the deposited melamine-formaldehyde condensation product is in a substantially water-insoluble condition.

6. A process of increasing the tensile strength of a fabric composed of substantially untwisted, unidirectionally oriented, non-woven, cellulosic fibers of the group consisting of cotton and rayon fibers which comprises treating said fibers with a colloidal aqueous solution of a. cationic polymerized melamine-formaldehyde condenration product, said colloidal aqueous solution containing 1.5 mols of formic acid for each mol of substantially monomeric melamine-formaldehyde condensation product, the take-up of the colloidal solution by the fabric being such as to deposit from about 0.5% to 25% by weight, based on the dry weight of the fabric, of the polymerized melamine-formaldehyde condensation product in the fabric, and thereafter curing the treated fabric whereby the deposited melamine-formaldehyde condensation product is in a substantially water-insoluble condition.

7. A process of increasing the tensile strength of a fabric composed of substantially untwisted, unidirectionally oriented, non-woven, cellulosic fibers of the group consisting of cotton and rayon fibers which comprises treating said fibers with a colloidal aqueous solution of a cationic polymerized melamine-formaldehyde condensation product, said colloidal aqueous solution containing 2-2.5 mols of glycolic acid for each mol of substantially monomeric melamine-formaldehyde condensation product, the take-up of the colloidal solution by the fabric being such as to deposit from about 0.5% to 25% by weight, based on the dry weight of the fabric, of the polymerized melamine-formaldehyde condensation product in the fabric, and thereafter curing the treated fabric whereby the deposited melamine-formaldehyde condensation product is in a substantially water-insoluble condition.

8. A process in accordance with claim 1 wherein the fabric is composed of all cotton fibers.

9. A process in accordance with claim 1 wherein the fabric is composed of all. viscose fibers.

10. A process in accordance with claim 1 wherein the fabric is composed of both cotton and viscose fibers.

ll. A process which consists of immersing a non-woven fabric composed of substantially untwisted, unidirectionally oriented unspun cotton and viscose fibers in equal proportions in a colloidal aqueous solution of cationic polymerized methylated trimethylol melamine prepared by aging 0.5 to 7.0 mols of lactic acid per mol of monomeric methylated trimethylol melamine in water at a temperature between 60 and 70 degrees Fahrenheit until a bluish haze appeared, thereafter pressing the wet fabric between squeeze rolls to reduce the pick-up of polymerized methylated trimethylol melamine on the fabric to between 5 and 10 per cent of the dry weight of the fabric, and thereafter heating the fabric at degrees centigrade for between 6 and 10 minutes to dry the fabric and cure the polymerized methylated trimethylol melamine to a substantially water-insoluble condition whereby the fill tensile strength of the fabric is substantially increased.

References Cited in the file of this patent UNITED STATES PATENTS 2,339,203 Stieglcr .ian. ll, 1944 2,345,543 Wohnsiedler et al Mar. 28, 194-4- 2,4l7,014 Pollard Mar. 4, 1947 2,423,428 Pollard July 1, 1947 2,485,030 Wohnsiedler et al .c Oct. 18, 1949 

1. A PROCESS OF INCREASING THE TENSILE STRENGTH OF A FABRIC COMPOSED OF SUBSTANTIALLY UNTWISTED, UNIDIRECTIONCALLY ORIENTED, NON-WOVEN, CELLULOSIC FIBERS OF THE GROUP CONSISTING OF COTTON AND RAYON FIBERS WHICH COMPRISES TREATING SAID FABRIC WITH A COLLOIDAL AQUEOUS SOLUTION OF A CATIONIC POLYMERIZED ALDEHYDE CONDENSATION PRODUCT OF AN AMINOTRIAZINE HAVING AT LEAST TWO AMINO GROUPS AND A HYDROGEN ATOM ATTACHED TO EACH AMINO NITROGEN ATOM, SAID COLLOIDAL AQUEOUS SOLUTION CONTAINING FROM 0.5 TO 7 MOLS OF A WATER-SOLUBLE MONOCARBOXYLIC ACID SELECTED FROM THE GROUP CONSISTING OF SATURATED ALIPHATIC HYDROCARBON AND HYDROXY HYDROCARBON ACIDS HAVING DISSOCIATION CONSTANTS BETWEEN ABOUT 1.4X10-5 AND 2.5X10-4 FOR EACH MOL OF SUBSTANTIALLY MONOMERIC ALDEHYDE CONDENSATION PRODUCT,THE TAKE-UP OF THE COLLOIDAL SOLUTION BY THE FABRIC BEING SUCH AS TO DEPOSIT FROM ABOUT 0.5 TO 25% BY WEIGHT, BASED ON THE DRY WEIGHT OF THE FABRIC, OF THE POLYMERIZED ALDEHYDE CONDENSATION PRODUCT IN THE FABRIC, AND THEREAFTER CURING THE TREATED FABRIC WHEREBY THE DEPOSITED ALDEHYDE CONDENSATION PRODUCT IS IN A SUBSTANTIALLY WATER-INSOLUBLE CONDITION.
 9. A PROCESS IN ACCORDANCE WITH CLAIM 1 WHEREIN THE FABRIC IS COMPOSED OF ALL VISCOSE FIBERS. 